Sahih al-Bukhari
Sahih al-Bukhari 507
To offer As-Salat (the prayer) facing a Rahila camel, a tree or a camel saddle as a Sutra).
Arabic hadith text
حَدَّثَنَا مُحَمَّدُ بْنُ أَبِي بَكْرٍ الْمُقَدَّمِيُّ، حَدَّثَنَا مُعْتَمِرٌ، عَنْ عُبَيْدِ اللَّهِ، عَنْ نَافِعٍ، عَنِ ابْنِ عُمَرَ، عَنِ النَّبِيِّ صلى الله عليه وسلم أَنَّهُ كَانَيُعَرِّضُ رَاحِلَتَهُ فَيُصَلِّي إِلَيْهَا. قُلْتُ أَفَرَأَيْتَ إِذَا هَبَّتِ الرِّكَابُ. قَالَ كَانَ يَأْخُذُ هَذَا الرَّحْلَ فَيُعَدِّلُهُ فَيُصَلِّي إِلَى آخِرَتِهِ ـ أَوْ قَالَ مُؤَخَّرِهِ ـوَكَانَ ابْنُ عُمَرَ ـ رضى الله عنه ـ يَفْعَلُهُ
Translation
Narrated Nafi`
"The Prophet (ﷺ) used to make his she-camel sit across and he would pray facing it (as a Sutra)." I asked, "What would the Prophet (ﷺ) do if the she-camel was provoked and moved?" He said, "He would take its camel-saddle and put it in front of him and pray facing its back part (as a Sutra). And Ibn `Umar used to do the same." (This indicates that one should not pray except behind a Sutra).